1. Field of the Invention
The present invention relates to systems for treating wastewater and, more particularly, to wastewater treatment systems that are modular in design.
2. Description of the Prior Art
Treating wastewater is important for a number of reasons. As the world""s population grows, the amount of water needed for consumption and other use continues to increase, while the amount of naturally available water remains the same. Thus, there is an ever increasing demand for usable, clean water, making the reclamation of tainted water extremely important.
In addition, as existing metropolitan areas become more crowded, developers are encouraged to construct new housing in previously undeveloped areas. Many such areas lack sufficient water for consumption, irrigation and similar purposes, necessitating the reclamation and reuse of available water resources.
One source of potentially reclaimable water is sewage from the residential use of water, commonly referred to as wastewater. Residential wastewater has a high water content, but requires substantial processing before it can be reused because of the human waste and other contaminants mixed with it.
A number of different systems have been proposed for treating sewage or wastewater. One such system, disclosed in U.S. Pat. No. 2,528,649, incorporates a simple sedimentation tank for separating solid waste, or xe2x80x9csludgexe2x80x9d, from water. The sludge is then passed to a digestion system where it is allowed to settle so that clear aqueous liquid separates from the sludge. The clear liquid is redirected back to the sedimentation tank. Unfortunately, this system suffers from a number of shortcomings that make it inefficient. First, the system makes no provision for increases in the volume of incoming sewage, either during high flow periods or as a community expands and therefore creates a larger amount of wastewater. In time, another complete treatment system would be required to handle the additional wastewater, resulting in unwanted expenses for the community. The system also incorporates a relatively crude sedimentation tank that merely allows the influent sewage to separate and does not aerate or facilitate processing of the sewage in any other way.
Another wastewater treatment system, described in U.S. Pat. No. 3,679,053 to Koulovatos et al., has three processing tanks for, respectively, receiving, aerating, and settling influent raw sewage. This system also fails to account for the possibility that the amount of influent sewage will increase over time. In addition, the disclosed system provides no overflow protection in case of large transient increases in the amount of sewage to be treated.
Yet another wastewater treatment system is disclosed in U.S. Pat. No. 3,920,550 to Farrell, Jr., et al. The Farrell system also has an aerobic and settling tank for aerating wastewater, and includes a sludge tank for receiving and further processing sludge separated from the supernatant water. However, it makes no provision for increases in the quantity of wastewater as a developing community expands. In addition, there is no disclosure of a plurality of parallel treatment tanks, nor of a system for controlling the operation of such tanks.
Accordingly, there is a need for a wastewater treatment system designed to accommodate increasing quantities of wastewater without requiring that an entirely new system be built. In addition, a need exists for a sewage treatment system that is designed and operated to be energy efficient. The present invention addresses these needs and others.
Briefly, and in general terms, the present invention is directed to a multi-phase system and method for treating wastewater. In an initial phase, the system is designed to treat a relatively small amount of wastewater, and includes at least one reactor tank and at least one other tank. The reactor tank processes the wastewater such that it separates into sludge and relatively clean water. The sludge is directed to the other tank for further processing.
In a subsequent phase (for treating larger quantities of wastewater), either the existing reactor tank is converted to a different type of tank, or the other tank is converted to another reactor tank, and additional reactor and/or digester tanks are provided. The number and size of those tanks is dependent upon the amount of additional wastewater to treat. In this manner, the costs of the system can be spread over several years, and the tanks built in the initial phase are all incorporated into the subsequent phases. In that manner, the footprint of the overall system is relatively small.
Thus, in one illustrative embodiment, the method of the present invention includes the steps of: providing plural tanks in an initial phase, including at least one reactor tank and at least one other tank; directing wastewater into the reactor tank for processing of the wastewater; directing waste from the reactor tank to the other tank for further processing; in a subsequent phase, converting one of the reactor tank and other tank into, respectively, a different type of tank or a reactor tank, and providing at least one more reactor tank or other tank; directing wastewater into the one or more reactor tanks for processing of the wastewater; and directing waste from the one or more reactor tanks to the one or more other tanks for further processing of the waste.
The system of the present invention is directed to a multi-phase system for treating wastewater, including: plural tanks, including at least one reactor tank and at least one digester tank; wherein at least one of the tanks is convertible for performing a first wastewater treatment function in an initial phase and a second wastewater treatment function in a subsequent phase.
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the features of the present invention.